An imaging apparatus calculates a depth of field, and when the calculated result is shallower than a set depth of field, the zoom operation at the telescopic side is switched to the electronic zoom. A user is capable of readily determining the focus state of a camera and confirming and adjusting the focus thereof with accuracy even in a display apparatus of a camera-equipped portable terminal device, where the size and resolution thereof are limited. The TFT includes an insulated substrate which is transparent, a source electrode and a drain electrode on the insulated substrate.